Wave Motion, writing an equation.

A sinusoidal wave traveling in the -x direction (to the left) has an amplitude of 20.0 cm, a wavelength of 29.0 cm, and a frequency of 15.0 Hz. The transverse position of an element of the medium at t = 0, x = 0 is y = -3.00 cm, and the element has a positive velocity here.

Write an expression for the wave function y(x,t), where y and x are expressed in cm, and t is expressed in seconds.

2. Relevant equations

[tex]\omega = 2\pif[/tex]

v=(lambda)(frequency)

[tex] k = 2\pi/\lambda[/tex]

[tex] y(x,t) = Asin[\left(2\pi/\lambda\right)(x - vt)][/tex]

3. The attempt at a solution
We are given the fact that:

[tex]A = 20.0cm[/tex]

[tex]\lambda = 29cm[/tex]

[tex] v = (lambda)(frequency) = 435cm/s[/tex]

I think the answer is the following, but I am not sure, and I only have one more submission left, so I want to be sure.

Your updated equation looks good. Once you plug in the numbers you found, you can check that it matches y=-3cm at x=0 and t=0 and that it also has a positive velocity (in the y direction at that point).

Now I was stupid and input [tex]y(x,t)20.0cos(0.217x+94.25t-0.1506)[/tex]...note I put cosine and not sine. Yes, the cosine would be correct with the right phase angle, but it's not with that phase angle.